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41.
Shoji Asano Keiji Itano Kohfuku Kohda Yuriko Yamagata 《Journal of heterocyclic chemistry》1996,33(4):1115-1121
Reaction of 9-substituted (methyl or benzyl) 1-aminoadenines 1 with hydrazine afforded 9-substituted 6-hydrazinopurines 2 and 1-substituted 5-ammo-4-(4-amino-1,2,4-triazol-3-yl)imidazole ( 4 ). The product ratio of 2 to 4 rose with increasing amounts of methanol used as the solvent. When the same reaction was carried out using 1,9-dimethyladenine instead of 1 , compounds 2 and 4 were also obtained with N6,9-dimethyladenine. A possible mechanism for formation of 2 and 4 is discussed. 相似文献
42.
Mat Rasol Awang Hassan Hamdani Mutaat Mohd. Shukri Mahmud Wan Badrin Wan Husain Tajuddin Osman Khomsaton Abu Bakar Asmahwati Kassim Zal U''yun Wan Mahmud Ishak ManafTamikazu Kume Shoji Hashimoto 《Radiation Physics and Chemistry》1993,42(4-6):611-616
In solid state fermentation, Pleurotus sajor-caju has been found to be able to degrade at least 30% oil palm empty Fruit Bunch (EFB) fibre leaving 70 % useful materials. Conditions under which fermentation carried out were investigated. It was found that, in the temperature range between 25– 28 °C, relative ph between 6–8, moisture between 60–70 % and medium composition of CaCO3: rice bran 2 %: 5 % were the optimum conditions. The results showed in fermented products that, there were substantial reduction in cellulosic component such as Crude Fiber (CF, 18 %); Acid Detergent Fibre (ADF, 45 %), Neutral Detergent Fibre (NDF, 61 %) and Acid Detergent Lignin (ADL, 14 %). However, Crude Protein (CP, 10%) increased resulted from single cell protein enrichment of mycelial microbial mass. The mass reductions of substrate in fermentation process corresponds to the CO2 released during fermentation. Hence, attributable to the decreased in content of CF, ADF, NDF, and ADL. The digestibility study has also been carried out to determine the useful level of this product to ruminant. Aflatoxin content was detected low in both the initial substrates and products. Based on nutritional value and low content of aflatoxin, the product is useful as a source of roughage to ruminant. 相似文献
43.
44.
Separability of some positional isomers of aromatic anions by capillary zone electrophoresis was improved by adding nonionic surfactants to a migrating solution. Eleven kinds of aromatic anions, including positional isomers, were used as analytes, and Brij-35, Brij-58 and Brij-78 were investigated as nonionic surfactants to form micelles, where hydrophobicities are different from each other. Increasing the concentration of the surfactants developed the separability of the anionic isomers. The interaction between the anions and the nonionic surfactant micelles is also investigated through the change in the electrophoretic mobility, and the binding constants are determined. Apparent electrophoretic mobility of the anions decreased with increasing concentrations of the nonionic surfactants. The decrease in the mobility, as well as the binding constant, was larger in the monovalent anions than in the divalent anions, which indicates that the interaction or reactivity of the monovalent analytes is higher than that of the divalent analytes. The reactivity of each anion was almost identical even when the kinds of the surfactants were changed, suggesting that the hydrophobicity of the polyoxyethylene group in the surfactant would have the main role for binding the analytes. The reactivity tendency among the positional isomers was almost similar to that in ion association-capillary zone electrophoresis using tertabutylammonium ion as a pairing ion. The results obtained in this work suggest that the anions are bound to the micelles by the hydrophobic interaction between analyte anions and the polyoxyethylene moiety of the surfactant micelles. Changes in the fluorescence intensity of the anions were also investigated; the results can explain well the mobility changes of the analytes. 相似文献
45.
Dr. Kazuto Suzuki Dr. Joshua Kyle Stanfield Dr. Keita Omura Dr. Yuma Shisaka Dr. Shinya Ariyasu Chie Kasai Dr. Yuichiro Aiba Dr. Hiroshi Sugimoto Prof. Dr. Osami Shoji 《Angewandte Chemie (International ed. in English)》2023,62(13):e202215706
Catching the structure of cytochrome P450 enzymes in flagrante is crucial for the development of P450 biocatalysts, as most structures collected are found trapped in a precatalytic conformation. At the heart of P450 catalysis lies Cpd I, a short-lived, highly reactive intermediate, whose recalcitrant nature has thwarted most attempts at capturing catalytically relevant poses of P450s. We report the crystal structure of P450BM3 mimicking the state in the precise moment preceding epoxidation, which is in perfect agreement with the experimentally observed stereoselectivity. This structure was attained by incorporation of the stable Cpd I mimic oxomolybdenum mesoporphyrin IX into P450BM3 in the presence of styrene. The orientation of styrene to the Mo-oxo species in the crystal structures sheds light onto the dynamics involved in the rotation of styrene to present its vinyl group to Cpd I. This method serves as a powerful tool for predicting and modelling the stereoselectivity of P450 reactions. 相似文献
46.
Konoike T Matsumura K Yorifuji T Shinomoto S Ide Y Ohya T 《The Journal of organic chemistry》2002,67(22):7741-7749
A practical multikilogram-scale synthesis of enantiomerically pure S-1255 (1), a potent and orally active ET(A) receptor antagonist, is described. Utilizing readily available starting materials and reagents, the entire sequence of reactions starting from 2,5-dihydroxyacetophenone 8 proceeded under mild conditions to give 1 in an excellent chemical yield (8 steps, 41% overall yield) and in a high enantiopurity (98% ee). The crucial step of the synthesis is a dynamic resolution of key intermediate 16. (R)-Methoxy acid (R)-16 having 97-99% ee was obtained in 83-84% yield from racemic 16 as a crystalline (1S,2R)-(+)-norephedrine or (+)-cinchonine salt by the dynamic resolution comprising concurrent crystallization and in situ racemization. A mechanism of the dynamic resolution through a ring-opened zwitterionic intermediate is discussed. In the final synthetic step, an effective carbon-carbon bond formation between the C4 carbon and the p-anisyl group was accomplished by a conjugate addition-elimination reaction of Grignard reagent 3 to (R)-16 to give 1 having 98% ee. Owing to high efficiencies of functional group transformations, carbon-carbon bond formations, and the dynamic resolution, the synthesis required no chromatographic purification and was amenable to a multikilogram-scale preparation. Several kilograms of 1 for clinical trials were successfully prepared by this process. 相似文献
47.
T Nishi F Saito H Nagahori M Kataoka Y Morisawa Y Yabe M Sakurai S Higashida M Shoji Y Matsushita 《Chemical & pharmaceutical bulletin》1990,38(1):103-109
Syntheses and biological activities of dipeptide renin inhibitors that contain statine analogues are described. The key steps of the synthetic approach to dipeptide renin inhibitors are the asymmetric synthesis of 2(R)-substituted-3-aminocarbonylpropionic acids and the diastereoselective syntheses of (3S,4S)-statine analogues. These inhibitors (2,14-40) inhibited human renin in the 3-140 nM range. Inhibitor ES 6864 (2) was found to be a highly potent inhibitor of human renin (IC50: 4.6 x 10(-9) M) and showed high enzyme specificity. Oral administration of ES 6864 at 3 mg/kg to conscious, sodium-depleted marmosets inhibited plasma renin activity (PRA) more than 80% after 1 h. 相似文献
48.
Shibuya H Kitamura C Maehara S Nagahata M Winarno H Simanjuntak P Kim HS Wataya Y Ohashi K 《Chemical & pharmaceutical bulletin》2003,51(1):71-74
The microbial transformation of four Cinchona alkaloids (quinine, quinidine, cinchonidine, and cinchonine) by endophytic fungi isolated from Cinchona pubescens was investigated. The endophytic filamentous fungus Xylaria sp. was found to transform the Cinchona alkaloids into their 1-N-oxide derivatives. 相似文献
49.
Ion association between inorganic anions and symmetrical tetraalkylammonium ions, R4N+ (R = Me, Et, Pr, n-Bu, n-Am, and 2-methyl butyl {isoamyl = iAm}) was investigated using ordinary silica capillary by capillary zone electrophoresis. An improved version of the Williams-Vigh method was used for the first time to measure the mobilities of the inorganic anions. Plots of log Kass against log dielectric constant in various media, revealed a smaller change in Kass compared to dielectric constant. These plots suggest that the Bjerrum's equation is inadequate in accounting for the associations of ions in a CZE setup. 相似文献
50.
Shibuya H Agusta A Ohashi K Maehara S Simanjuntak P 《Chemical & pharmaceutical bulletin》2005,53(7):866-867
The microbial transformation of (+)-catechin (1) and (-)-epicatechin (2) by endophytic fungi isolated from a tea plant was investigated. It was found that the endophytic filamentous fungus Diaporthe sp. transformed them (1, 2) into the 3,4-cis-dihydroxyflavan derivatives, (+)-(2R,3S,4S)-3,4,5,7,3',4'-hexahydroxyflavan (3) and (-)-(2R,3R,4R)-3,4,5,7,3',4'-hexahydroxyflavan (7), respectively, whereas (-)-catechin (ent-1) and (+)-epicatechin (ent-2) with a 2S-phenyl group resisted the biooxidation. 相似文献